usb: gadget: fastboot: Add fastboot erase

Adds the fastboot erase functionality, to erase a partition
specified by name. The erase is performed based on erase group size,
to avoid erasing other partitions. The start address and the size
is aligned to the erase group size for this.

Currently only supports erasing from eMMC.

Signed-off-by: Dileep Katta <dileep.katta@linaro.org>
Reviewed-by: Lukasz Majewski <l.majewski@samsung.com>

common/fb_mmc.c

@@ -10,6 +10,7 @@
 #include <part.h>
 #include <aboot.h>
 #include <sparse_format.h>
+#include <mmc.h>
 
 #ifndef CONFIG_FASTBOOT_GPT_NAME
 #define CONFIG_FASTBOOT_GPT_NAME GPT_ENTRY_NAME
@@ -110,3 +111,58 @@ void fb_mmc_flash_write(const char *cmd, void *download_buffer,
 		write_raw_image(dev_desc, &info, cmd, download_buffer,
 				download_bytes);
 }
+
+void fb_mmc_erase(const char *cmd, char *response)
+{
+	int ret;
+	block_dev_desc_t *dev_desc;
+	disk_partition_t info;
+	lbaint_t blks, blks_start, blks_size, grp_size;
+	struct mmc *mmc = find_mmc_device(CONFIG_FASTBOOT_FLASH_MMC_DEV);
+
+	if (mmc == NULL) {
+		error("invalid mmc device");
+		fastboot_fail("invalid mmc device");
+		return;
+	}
+
+	/* initialize the response buffer */
+	response_str = response;
+
+	dev_desc = get_dev("mmc", CONFIG_FASTBOOT_FLASH_MMC_DEV);
+	if (!dev_desc || dev_desc->type == DEV_TYPE_UNKNOWN) {
+		error("invalid mmc device");
+		fastboot_fail("invalid mmc device");
+		return;
+	}
+
+	ret = get_partition_info_efi_by_name(dev_desc, cmd, &info);
+	if (ret) {
+		error("cannot find partition: '%s'", cmd);
+		fastboot_fail("cannot find partition");
+		return;
+	}
+
+	/* Align blocks to erase group size to avoid erasing other partitions */
+	grp_size = mmc->erase_grp_size;
+	blks_start = (info.start + grp_size - 1) & ~(grp_size - 1);
+	if (info.size >= grp_size)
+		blks_size = (info.size - (blks_start - info.start)) &
+				(~(grp_size - 1));
+	else
+		blks_size = 0;
+
+	printf("Erasing blocks " LBAFU " to " LBAFU " due to alignment\n",
+	       blks_start, blks_start + blks_size);
+
+	blks = dev_desc->block_erase(dev_desc->dev, blks_start, blks_size);
+	if (blks != blks_size) {
+		error("failed erasing from device %d", dev_desc->dev);
+		fastboot_fail("failed erasing from device");
+		return;
+	}
+
+	printf("........ erased " LBAFU " bytes from '%s'\n",
+	       blks_size * info.blksz, cmd);
+	fastboot_okay("");
+}

doc/README.android-fastboot

@@ -6,9 +6,8 @@ Overview
 The protocol that is used over USB is described in
 README.android-fastboot-protocol in same directory.
 
-The current implementation does not yet support the erase command or the
-"oem format" command, and there is minimal support for the flash command;
-it only supports eMMC devices.
+The current implementation is a minimal support of the erase command,the
+"oem format" command and flash command;it only supports eMMC devices.
 
 Client installation
 ===================

drivers/usb/gadget/f_fastboot.c

@@ -535,6 +535,28 @@ static void cb_oem(struct usb_ep *ep, struct usb_request *req)
 	}
 }
 
+#ifdef CONFIG_FASTBOOT_FLASH
+static void cb_erase(struct usb_ep *ep, struct usb_request *req)
+{
+	char *cmd = req->buf;
+	char response[RESPONSE_LEN];
+
+	strsep(&cmd, ":");
+	if (!cmd) {
+		error("missing partition name");
+		fastboot_tx_write_str("FAILmissing partition name");
+		return;
+	}
+
+	strcpy(response, "FAILno flash device defined");
+
+#ifdef CONFIG_FASTBOOT_FLASH_MMC_DEV
+	fb_mmc_erase(cmd, response);
+#endif
+	fastboot_tx_write_str(response);
+}
+#endif
+
 struct cmd_dispatch_info {
 	char *cmd;
 	void (*cb)(struct usb_ep *ep, struct usb_request *req);
@@ -561,6 +583,9 @@ static const struct cmd_dispatch_info cmd_dispatch_info[] = {
 	{
 		.cmd = "flash",
 		.cb = cb_flash,
+	}, {
+		.cmd = "erase",
+		.cb = cb_erase,
 	},
 #endif
 	{

include/fb_mmc.h

@@ -6,3 +6,4 @@
 
 void fb_mmc_flash_write(const char *cmd, void *download_buffer,
 			unsigned int download_bytes, char *response);
+void fb_mmc_erase(const char *cmd, char *response);